Bug 968409 - Add FrameworkHelper for UITests; r=mcomella

mobile/android/base/tests/helpers/FrameworkHelper.java

@@ -0,0 +1,90 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.tests.helpers;
+
+import static org.mozilla.gecko.tests.helpers.AssertionHelper.*;
+
+import org.mozilla.gecko.tests.UITestContext;
+
+import java.lang.reflect.Field;
+
+import android.content.Context;
+import android.view.View;
+
+/**
+ * Provides helper functions for accessing Android framework features
+ *
+ * This class uses reflection to access framework functionalities that are
+ * unavailable through the regular Android API. Using reflection in this
+ * case is okay because it does not touch Gecko classes that go through
+ * ProGuard.
+ */
+public final class FrameworkHelper {
+
+    private FrameworkHelper() { /* To disallow instantiation. */ }
+
+    private static Field getClassField(final Class<?> clazz, final String fieldName)
+            throws NoSuchFieldException {
+        Class<?> cls = clazz;
+        do {
+            try {
+                return cls.getDeclaredField(fieldName);
+            } catch (final NoSuchFieldException e) {
+                cls = cls.getSuperclass();
+            }
+        } while (cls != null);
+        // We tried getDeclaredField before; now try getField instead.
+        // getField behaves differently in that getField traverses the inheritance
+        // list, but it only works on public fields. While getField won't get us
+        // anything new, it makes code cleaner by throwing an exception for us.
+        return clazz.getField(fieldName);
+    }
+
+    private static Object getField(final Object obj, final String fieldName) {
+        try {
+            final Field field = getClassField(obj.getClass(), fieldName);
+            final boolean accessible = field.isAccessible();
+            field.setAccessible(true);
+            final Object ret = field.get(obj);
+            field.setAccessible(accessible);
+            return ret;
+        } catch (final NoSuchFieldException e) {
+            // We expect a valid field name; if it's not valid,
+            // the caller is doing something wrong and should be fixed.
+            fail("Argument field should be a valid field name: " + e.toString());
+        } catch (final IllegalAccessException e) {
+            // This should not happen. If it does, setAccessible above is not working.
+            fail("Field should be accessible: " + e.toString());
+        }
+        throw new IllegalStateException("Should not continue from previous failures");
+    }
+
+    private static void setField(final Object obj, final String fieldName, final Object value) {
+        try {
+            final Field field = getClassField(obj.getClass(), fieldName);
+            final boolean accessible = field.isAccessible();
+            field.setAccessible(true);
+            field.set(obj, value);
+            field.setAccessible(accessible);
+            return;
+        } catch (final NoSuchFieldException e) {
+            // We expect a valid field name; if it's not valid,
+            // the caller is doing something wrong and should be fixed.
+            fail("Argument field should be a valid field name: " + e.toString());
+        } catch (final IllegalAccessException e) {
+            // This should not happen. If it does, setAccessible above is not working.
+            fail("Field should be accessible: " + e.toString());
+        }
+        throw new IllegalStateException("Cannot continue from previous failures");
+    }
+
+    public static Context getViewContext(final View v) {
+        return (Context) getField(v, "mContext");
+    }
+
+    public static void setViewContext(final View v, final Context c) {
+        setField(v, "mContext", c);
+    }
+}